Add test for C source depending on Haskell C stub

cabal-testsuite/PackageTests/FFI/CSourceDependsStub/Lib.hs

@@ -0,0 +1,13 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+module Lib where
+
+import Foreign.C (CInt (..))
+
+hello :: IO CInt
+hello = do
+  putStrLn "hello!"
+  return 11
+
+foreign export ccall "hello" hello :: IO CInt
+

cabal-testsuite/PackageTests/FFI/CSourceDependsStub/Main.hs

@@ -0,0 +1,16 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+module Main where
+
+import Foreign.C (CInt (..))
+
+foreign import ccall "meaning_of_life_c"
+  meaning_of_life_c :: IO CInt
+
+main :: IO ()
+main = do
+    secret <- meaning_of_life_c
+    -- The value 11 comes from the exported Lib.hello
+    if (secret == 11)
+        then putStrLn ("The secret is " ++ show secret)
+        else error ("Expected value 11, got " ++ show secret)

cabal-testsuite/PackageTests/FFI/CSourceDependsStub/cabal.project

@@ -0,0 +1 @@
+packages: .

cabal-testsuite/PackageTests/FFI/CSourceDependsStub/cabal.test.hs

@@ -0,0 +1,6 @@
+-- Tests whether an extra C source can depend on a _stub header generated by
+-- GHC compiling a Haskell module with a foreign export declaration
+
+import Test.Cabal.Prelude
+main = cabalTest $ do
+    cabal "v2-build" []

cabal-testsuite/PackageTests/FFI/CSourceDependsStub/cbits/clib.c

@@ -0,0 +1,5 @@
+#include "Lib_stub.h"
+
+int meaning_of_life_c() {
+    return hello();
+}

cabal-testsuite/PackageTests/FFI/CSourceDependsStub/csourcedepsstub.cabal

@@ -0,0 +1,16 @@
+cabal-version:       2.2
+name:                csourcedepsstub
+version:             0.1
+build-type:          Simple
+
+library
+  build-depends:       base
+  default-language:    Haskell2010
+  include-dirs:        cbits
+  c-sources:           cbits/clib.c
+  exposed-modules:     Lib
+
+executable csourcedeps-exe
+  main-is:             Main.hs
+  build-depends:       base, csourcedepsstub
+  default-language:    Haskell2010